Annotation of the results obtained in 2019
Effect of Photoelectrochemical Photocurrent Switching was demonstrated for pristine nanostructured anodized TiO2 for the first time. Photoelectrochemical response was tested for several wavelengths and potential biases. This switching is associated with Ti3 + states that arise in the band gap during phase-forming annealing of TiO2 nanotubes after their formation during anodization of titanium. Suggested mimicking of logic functions in aqueous solutions allows further integration of element into communication with living objects [Ryzhkov, N. V., Yurova, V. Yu., Brezhneva, N. Yu., Ulasevich, S. A., Skorb, E. V. (2020): Photoelectrochemical Photocurrent Switching Effect in Nanostructured Anodized Titanium Dioxide and Enhancement of its Photocatalytic Activity by Layer-by-layer Polyelectrolyte Assembly, RENSIT, 12, 153-160. DOI: 10.17725/rensit.2020.12.153]. Iontronics is a perspective way of information transduction in solutions. Shannon entropy is a key concept of information theory. We discussed Shannon entropy in relation to ion distribution in solutions. We studied entropy associated with ions redistribution using model electrochemically triggered local ion fluxes. For this purpose, we utilized bare gold electrodes as well as covered by polyelectrolyte layers and lipids. Modification of the electrode surface leads to a change of ion flux triggered by hydroquinone oxidation. Consequently, various distribution of ions in solution can be obtained. Shannon entropy was evaluated for diverse ion distributions [Ryzhkov, N. V., Yurova, V. Yu., Skorb, E. V. Shannon entropy associated with electrochemically generated ion concentration gradients– ITMO - special issue of Nanosystems: Physics, Chemistry, Mathematics - Nanosystems: Physics, Chemistry, Mathematics DOI: 10.17586/2220-8054-2020-11-2-171-175]. The Ti/TiO2 system was demonstrated to be simple and robust model of chemical logic gates. Realization of OR and XOR logic gates with blue and UV light as input signals, photocurrent as output signal and applied potential bias as programming input was demonstrated. Suggested mimicking of logic functions in aqueous solutions allows further integration of element into communication with living objects [Ryzhkov, N. V., Yurova, V. Yu., Ulasevich, S. A., Skorb, E. V. (2020): Photoelectrochemical Photocurrent Switching Effect on Pristine Anodized Ti/TiO2 System as a Platform for Chemical Logic Device, RCS Advances, DOI: 10.1039/D0RA00205D]. The possibility of increasing the photoactivity of nanostructured anodized TiO2 by the deposition of polyelectrolyte multilayers on its surface was also demonstrated. Thus, TiO2 / (PSS / PEI) 3 exhibits three times greater photoelectrochemical activity compared to unmodified TiO2 due to buffering effect of polyelectrolyte multilayer containing weak proton sponging polycation and proton transport polyanion [Ryzhkov, N. V., Yurova, V. Yu., Brezhneva, N. Yu., Ulasevich, S. A., Skorb, E. V. (2020): Photoelectrochemical Photocurrent Switching Effect in Nanostructured Anodized Titanium Dioxide and Enhancement of its Photocatalytic Activity by Layer-by-layer Polyelectrolyte Assembly, RENSIT, 12, 153-160. DOI: 10.17725/rensit.2020.12.153]. A novel approach for remotely controlled manipulation of lipid bilayers was presented. Layer-by-Layer deposition of polyethyleneimine and poly(sodium 4-styrenesulfonate) on nanostructured TiO2 photoanode was performed to obtain the surface of the desired net charge and enhance photocatalytic performance. The lipid bilayer was deposited on top of a multi-layer positive polymer cushion from the dispersion of negative vesicles. The separation distance between the electrostatically linked polyelectrolyte cushion and the lipid bilayer can be adjusted by changing the environmental pH, as zwitter-ionic lipid molecules undergo pH-triggered charge-shifting. The proton generation was performed remotely by photoanodic water decomposition on the TiO2 surface under 365 nm illumination. The light-induced reversible detachment of lipid bilayer from polymer cushioned photoactive substrate is found to be correlated with suggested impedance models. Model of adaptive light responsive biointerface were suggested. [Ryzhkov, N. V., Mamchik, N. A., & Skorb, E. V. (2019). Electrochemical triggering of lipid bilayer lift-off oscillation at the electrode interface. Journal of the Royal Society Interface, 16(150), 20180626].

 

Publications

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Annotation of the results obtained in 2017
The properties of differently nanoarchitectured heterostructures based on semiconductor / polyelectrolyte colloidal particles and planar systems are in focus during first year of the project for the following project aim of dynamic non-linear oscillation of coatings for optics. For different heterostructures the mechanisms of formation of systems with fast and reliable light activation characteristics on different wavelengths are chosen. Systems are investigated under different intensity and duration of irradiation. Optimal parameters of heterostructures synthesis and assemblies are chosen, e.g. pH and ionic strength of solutions for polyelectrolyte assemblies, photosensitivity of composite heterostructures, e.g. based on titania. Complex study of physico-chemical properties and morphology of nanoarchitectured assemblies and structures is evaluated with the set of available modern physicochemical methods. High attention is paid to in situ monitoring of the system due to following needs of the oscillation non-linear materials for optics that can be pronounced activated in time and space. The consequences of heterostructures protonation are evaluated depending on system nanoarchitecture to answer in following the promising sustainable systems with reliable activation, relaxation behavior and stability. The structures sensitive to visible light is synthesized and characterized. The interplay between a number of pH sensitive polyelectrolyte layers in the system, concentration of photoactive materials, and system nanoarchitecture will be chosen for sustainable application. The study of morphological and chemical changes in the heterostructure depending on its composition is reported. The role of substrate and its transparence on the precise location of activation affect and system response is evaluated. Mechanisms of light activated processes in thin films of different composition is studied together with the evolution of optical properties of thin film heterostructures. In an effort to control the photoelectronic and photomechanical interaction between an inorganic surface and a defined polymeric coating, we present in EPL 2017 a new and easy method of a cellulose-based hybrid formation. We used Schweizer’s reagent, a specific copper ammonia hydroxide-based solvent for cotton dissolution and found the optimal concentration for the formation of photosensitive uniform cellulose coating on titania, TiO2-cellulose coating and free-standing hybrid. Photomobility, the material mobility induced by light, of a cellulose layer on a titania surface and of a TiO2-cellulose hybrid on a silicon wafer has been studied. This can be used for photohealing, and the most promising system is the one that can be healed with light due to in situ activation of titania nanoparticles assembled on cellulose fibers in a hydrogel. The interfacial contact between titania particles and fiber is important for local transport of electrons and ions, thus the most promising system was obtained by in situ synthesis of titania nanoparticles on cellulose dispersed in Schweizer’s reagent. We propose that cellulose coatings on titania surface and free-standing hybrids can be applicable for a wide range of photochemical devices: films for optics, drug delivery systems, and inks for printing of biologically relevant lab-on-chips. Taking into account the interest of photoregulated biomaterials, the methodics of using a chitosan nanolayer as an efficient pH buffer to protect pH-sensitive supramolecular assemblies is suggested in Phys. Chem. Chem. Phys. 2017. It is attractive to control the properties of macro objects and films by employing simple nanolayer composites, as in the case of nanoarchitectured Layer-by-Layer (LbL) coating. In this paper, we use chitosan as a surface-based pH buffer to protect adsorbed supramolecular fibres from pH-mediated disassembly. Protons are generated on a titania surface under illumination at 405 nm leading to an appreciable pH change on the surface. We find that supramolecular polymers that are highly sensitive to pH change will not disassemble after irradiation if a nanolayer of chitosan is present. We propose that chitosan can be used as an efficient pH-responsive protective layer for pH sensitive soft materials. Bioinspiration is an attractive way to develop new robust chemistry. In biological cell, chemical reactions form complex networks (e.g. signaling and metabolic) that communicate with each other and control cell division, growth, and interaction with environment. Thus, combining multiple chemical subsystems into a single network is an attractive way to design a chemical system with new functions. Besides suggesting four-variable model of an enzymatic oscillator based on trypsin (Israel J. Chem. 2018), in the paper ChemCatChem, 2018, we combined two chemical networks: i) a photocatalytic oxidation/reduction on TiO2 particles, and ii) an autocatalytic formation of enzyme trypsin (Tr) from its precursor trypsinogen (Tg). Moreover, we put the combined network in hydrogel media, where all reactions are coupled to diffusion, to achieve a photocatalytic regulation of an autocatalytic wave. We showed that TiO2 particles affected the fluorescence quenching of Tr, but, without irradiation, had no effect on the autocatalytic formation of Tr. With irradiation, however, a cascade of photocatalytic reactions causes media acidification that suppress the autocatalytic formation of Tr and propagation of the autocatalytic wave.

 

Publications

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Annotation of the results obtained in 2018
The second year of the project was related to various aspects. We have analyzed an importance of buffering nanolayer position in Layer-by-Layer (LbL) assembly on titania based hybrid photoactivity. Nanoarchitecture of LbL films is a convenient and simple way to control the photoelectrochemical properties of the semiconductor films. Hereby, we used the combination of polystyrenesulfonate (PSS) and polyethyleneimine (PEI) deposited on the titania film for controlling the photochemical response of the hybrid system. Photogenerated protons on the titania surface are responsible for the acidity change near the irradiated surface. We investigated that the photogenerated protons being absorbed by PEI spatially separated from the TiO2 surface with the nanoscale-thick PSS layer (with thickness ca. 5 nm) lead to the sufficient decrease in photoactivity of the hybrid system TiO2/PSS/PEI ca. 4 times in comparison with pristine TiO2. PEI nanolayer being deposited directly on the TiO2 surface can decrease the photoactivity of the system ca. 2–2.5 times (Sol-Gel Sci. Technol., 2019, 89, 92-100). In situ studies of transmembrane channels often require a model bioinspired artificial lipid bilayer (LB) decoupled from its underlaying support. Obtaining free-standing lipid membranes is still a challenge. In this study, we suggest an electrochemical approach for LB separation from its solid support via hydroquinone oxidation. Layer-by-layer deposition of PEI and PSS on the electrode was performed to obtain a polymeric nanocushion of [PEI/PSS]3/PEI. The proton generation associated with hydroquinone oxidation was studied using scanning vibrating electrode (SVET) and scanning ion-selective electrode techniques (SIET). Electrochemical impedance spectroscopy is suggested to be a powerful instrument for the in situ observation of processes associated with the LB–solid support interface (Royal Society Interface, 2019, 16, 20180626.). Due to interest for titanium implant surface nanostructuring the influence of surface nanotopography of sonochemically generated mesoporous titania coatings (TMS) on the adhesion, proliferation, and osteogenic differentiation of human mesenchymal stem cells (hMSCs) have been investigated in vitro for the first time. It has been revealed that adhesion and proliferation of hMSCs is higher on TMS surfaces compared to smooth polished titania surface after five days of incubation. Surprisingly, the sonochemically generated disordered nanotopography induces the differentiation of hMSCs into osteogenic direction in the absence of osteogenic medium. Thus sonochemical nanostructuring of titanium based implants stimulates the regenerative process of bone tissue. (Ultrasonic Sonochem. 2019, 52, 437-445). As photoactive materials we synthesized and studied thin films of bismuth oxysulfide (BOS) semiconductor films in aqueous solutions containing acceptors of photoelectrons. The anomalously high giant incident photon-to-current conversion efficiency (IPCE) was related to the photoconductivity of the semiconductor. In the work, we analyzed the dynamics of the chemical and phase composition of BOS films with variation of their deposition time, as well as the dependence of photocurrent on the film thickness and wavelength of the incident light (Phys. Chem. Chem. Phys. 2018, 20, 20340-20346 (+outside front cover page). Blind and color blind people cannot use colorimetric diagnostics; the problem is especially severe in rural areas where high temperatures and the absence of electricity challenge modern diagnostics. Here we propose to replace the unstable component of a diagnostic test, H2O2, with stable TiO2. Under UV irradiation, TiO2 forms reactive oxygen species that initiate polymerization of acrylamide causing liquid-to-gel transition in an analyte-dependent manner. We demonstrate that specific DNA sequences can be detected using this approach. This development may enable the detection of biological molecules by users with limited resources, for example in developing countries or for travelers in remote areas. (RCS Advances. 2018, 8, 37735 – 37739). Moreover, the development of stimuli-responsive nanocontainers is an issue of utmost importance for many applications such as targeted drug delivery, regulation of the cell and tissue behavior, making bacteria have useful functions and here converting light. The present work shows a new contribution to the design of polyelectrolyte (PE) containers based on surface modified mesoporous titania particles with deposited Ag nanoparticles to achieve chemical light upconversion via biofilms. The PE shell allows slowing down the kinetics of a release of loaded L-arabinose and switching the bacteria luminescence in a certain time. The hybrid containers activated at 980 nm illumination demonstrate 10 times faster release of L-arabinose as opposed to nonactivated containers. Fast IR-released L-arabinose switch bacteria fluorescence which we monitor at 510 nm. The approach described herein can be used in many applications where the target and delayed switching and light upconversion are required (Bioconjugate Chem. 2018, 29, 3793-3799.) We summarize our results and ideas by showing how the research moved from light-regulated feedback sustainable systems and control biodevices to the current focus on infochemistry in aqueous solution. An important advanced characteristic of such materials and devices is the pH concentration gradient in aqueous solution. We prove that pH-regulated polyelectrolytes multilayers can change their properties film thickness and stiffness, permeability, hydrophilicity, and/or fluorescence in response to light or electrochemical or biological processes instead of classical acid/base titration (Langmuir, 2019, DOI: 10.1021/acs.langmuir.9b00633). The second year of the project was related to various aspects. We have analyzed an importance of buffering nanolayer position in Layer-by-Layer (LbL) assembly on titania based hybrid photoactivity. Nanoarchitecture of LbL films is a convenient and simple way to control the photoelectrochemical properties of the semiconductor films. Hereby, we used the combination of polystyrenesulfonate (PSS) and polyethyleneimine (PEI) deposited on the titania film for controlling the photochemical response of the hybrid system. Photogenerated protons on the titania surface are responsible for the acidity change near the irradiated surface. We investigated that the photogenerated protons being absorbed by PEI spatially separated from the TiO2 surface with the nanoscale-thick PSS layer (with thickness ca. 5 nm) lead to the sufficient decrease in photoactivity of the hybrid system TiO2/PSS/PEI ca. 4 times in comparison with pristine TiO2. PEI nanolayer being deposited directly on the TiO2 surface can decrease the photoactivity of the system ca. 2–2.5 times (Sol-Gel Sci. Technol., 2019, 89, 92-100). In situ studies of transmembrane channels often require a model bioinspired artificial lipid bilayer (LB) decoupled from its underlaying support. Obtaining free-standing lipid membranes is still a challenge. In this study, we suggest an electrochemical approach for LB separation from its solid support via hydroquinone oxidation. Layer-by-layer deposition of PEI and PSS on the electrode was performed to obtain a polymeric nanocushion of [PEI/PSS]3/PEI. The proton generation associated with hydroquinone oxidation was studied using scanning vibrating electrode (SVET) and scanning ion-selective electrode techniques (SIET). Electrochemical impedance spectroscopy is suggested to be a powerful instrument for the in situ observation of processes associated with the LB–solid support interface (Royal Society Interface, 2019, 16, 20180626.). Due to interest for titanium implant surface nanostructuring the influence of surface nanotopography of sonochemically generated mesoporous titania coatings (TMS) on the adhesion, proliferation, and osteogenic differentiation of human mesenchymal stem cells (hMSCs) have been investigated in vitro for the first time. It has been revealed that adhesion and proliferation of hMSCs is higher on TMS surfaces compared to smooth polished titania surface after five days of incubation. Surprisingly, the sonochemically generated disordered nanotopography induces the differentiation of hMSCs into osteogenic direction in the absence of osteogenic medium. Thus sonochemical nanostructuring of titanium based implants stimulates the regenerative process of bone tissue. (Ultrasonic Sonochem. 2019, 52, 437-445). As photoactive materials we synthesized and studied thin films of bismuth oxysulfide (BOS) semiconductor films in aqueous solutions containing acceptors of photoelectrons. The anomalously high giant incident photon-to-current conversion efficiency (IPCE) was related to the photoconductivity of the semiconductor. In the work, we analyzed the dynamics of the chemical and phase composition of BOS films with variation of their deposition time, as well as the dependence of photocurrent on the film thickness and wavelength of the incident light (Phys. Chem. Chem. Phys. 2018, 20, 20340-20346 (+outside front cover page). Blind and color blind people cannot use colorimetric diagnostics; the problem is especially severe in rural areas where high temperatures and the absence of electricity challenge modern diagnostics. Here we propose to replace the unstable component of a diagnostic test, H2O2, with stable TiO2. Under UV irradiation, TiO2 forms reactive oxygen species that initiate polymerization of acrylamide causing liquid-to-gel transition in an analyte-dependent manner. We demonstrate that specific DNA sequences can be detected using this approach. This development may enable the detection of biological molecules by users with limited resources, for example in developing countries or for travelers in remote areas. (RCS Advances. 2018, 8, 37735 – 37739). Moreover, the development of stimuli-responsive nanocontainers is an issue of utmost importance for many applications such as targeted drug delivery, regulation of the cell and tissue behavior, making bacteria have useful functions and here converting light. The present work shows a new contribution to the design of polyelectrolyte (PE) containers based on surface modified mesoporous titania particles with deposited Ag nanoparticles to achieve chemical light upconversion via biofilms. The PE shell allows slowing down the kinetics of a release of loaded L-arabinose and switching the bacteria luminescence in a certain time. The hybrid containers activated at 980 nm illumination demonstrate 10 times faster release of L-arabinose as opposed to nonactivated containers. Fast IR-released L-arabinose switch bacteria fluorescence which we monitor at 510 nm. The approach described herein can be used in many applications where the target and delayed switching and light upconversion are required (Bioconjugate Chem. 2018, 29, 3793-3799.) We summarize our results and ideas by showing how the research moved from light-regulated feedback sustainable systems and control biodevices to the current focus on infochemistry in aqueous solution. An important advanced characteristic of such materials and devices is the pH concentration gradient in aqueous solution. We prove that pH-regulated polyelectrolytes multilayers can change their properties film thickness and stiffness, permeability, hydrophilicity, and/or fluorescence in response to light or electrochemical or biological processes instead of classical acid/base titration (Langmuir, 2019, DOI: 10.1021/acs.langmuir.9b00633).

 

Publications

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